Control valve with improved sealing for a fluid circulation system

ABSTRACT

A control valve ( 10 ) for a fluid circulation circuit comprises a body ( 12 ) which is equipped with a fluid inlet ( 18 ) and with at least two fluid outlets ( 20, 22, 24 ) and which delimits a housing of revolution for an adjusting element ( 26 ) able to rotate about an axis of rotation (XX) and to adopt various angular positions to control the distribution of fluid through the outlets. The adjusting member ( 26 ) is surrounded by a sealing ring ( 42 ) in the form of an open annulus, which rotates as one with the adjusting member and is arranged with a small clearance around the adjusting member, this allowing the sealing ring to be pressed firmly internally against a side wall ( 16 ) into which the fluid outlets ( 20, 22, 24 ) open with a view to ensuring sealing under the action of the pressure of the fluid. Application in particular to motor vehicle fluid circuits.

The invention relates to a control valve intended for a fluidcirculation circuit, particularly for a motor vehicle combustion enginecooling circuit.

The valve of the invention is of the type comprising a body which isequipped with a fluid inlet and with at least two fluid outlets andwhich delimits a housing of revolution for an adjusting element able torotate about an axis of rotation and to adopt various angular positionsto control the distribution of fluid through the outlets, the bodycomprising an end wall into which the fluid inlet opens and a side wallinto which the fluid outlets open.

Such a valve may be qualified as a “rotary valve” in so far as itsadjusting member rotates about an axis of rotation. In a valve of thistype, the side wall usually delimits a cylindrical housing able toaccommodate the adjusting member which has a homologous cylindricalshape.

The fluid that enters the valve body via the fluid inlet is distributedbetween the fluid outlets according to the angular position of theadjusting member.

In a control valve of this type, it is necessary to ensure sealingbetween the adjusting member and the side wall of the valve body. Thissealing is aimed at preventing any accidental leak of fluid to an outletwhen this outlet is supposed to be closed off by the adjusting member.

Various solutions have already been proposed in order to ensure suchsealing.

This sealing may be provided directly by contact between the respectivematerials of the valve body and of the adjusting member.

Sealing may also call upon an intermediate seal, for example in the formof a liner, interposed between the adjusting member and the side wall ofthe valve body.

In all these known solutions, contact between the adjusting member andthe side wall of the valve body tends to generate friction which has tobe overcome when the adjusting member is turned.

This therefore entails a significant force, either by hand or by way ofan actuator, when performing said turning.

It is a particular object of the invention to overcome theaforementioned disadvantages.

The invention is aimed in particular at affording a control valve of theabove type in which friction between the adjusting member and the valvebody is reduced, while at the same time guaranteeing better sealingbetween these components.

According to the invention, the adjusting member is surrounded by asealing ring in the form of an open annulus, which rotates as one withthe adjusting member and is arranged with a small clearance around theadjusting member, this allowing the sealing ring to be pressed firmlyinternally against the side wall with a view to ensuring sealing underthe action of the pressure of the fluid.

Thus, sealing is ensured by the pressure of the fluid which becomesembroiled between the adjusting member proper and the sealing ring,because of the clearance there is between them.

This solution entails that there be an annular space, even a partialone, between the adjusting member and the sealing ring to allow thefluid to access this region and exert its pressure against the sealingring.

Furthermore, this solution offers the advantage of compensating for wearof the sealing ring.

The clearance between the adjusting member and the sealing ring is, forexample, 1/10 to 1 mm, particularly around 3/10 mm.

In the invention, the sealing ring is made of a material with a lowcoefficient of friction. It may in particular be a material of thepolyamide type or alternatively of the polytetrafluoroethylene (PTFE)type.

According to another feature of the invention, the sealing ringcomprises a smooth exterior surface into which a multitude of uniformlyspaced blind holes open, this making it possible to reduce the area ofcontact between the sealing ring and the side wall.

This reduction in the contact area contributes to reducing the frictionwithout compromising the sealing.

Advantageously, the ratio between the surface area of the blind holesand the smooth surface area of the sealing ring is between 25% and 40%.This ratio is preferably close to 33%.

The blind holes, which are not through-holes, advantageously have acircular contour. In particular, they may each have the form of a cap ofa sphere.

According to yet another feature of the invention, the adjusting memberand the sealing ring have reliefs of mating shapes to allow them to bemade to rotate as one.

In a preferred embodiment of the invention, the side wall of the valvebody delimits a cylindrical housing and the sealing ring has acylindrical exterior surface.

In one embodiment, the fluid inlet opens axially into the end wall,whereas the fluid outlets open radially into the side wall of the valvebody.

According to another aspect, the invention relates to a fluidcirculation circuit, comprising a control valve as defined hereinabove,the fluid inlet of which is connected to a fluid source and the fluidoutlets of which are connected respectively to branches of the circuit.

Such a circuit is advantageously produced in the form of a coolingcircuit for the combustion engine of a motor vehicle, through which acooling fluid passes under the action of a circulation pump.

The control valve therefore advantageously constitutes a three-wayvalve, the fluid inlet of which is connected to an intake for coolingfluid arriving from the engine and the three fluid outlets of which areconnected respectively to a first branch of the circuit which contains acooling radiator, to a second branch of the circuit which bypasses thecooling radiator, and to a third branch of the circuit which contains aheater matrix for heating the cabin.

In the description that follows, given solely by way of example,reference is made to the attached drawings, in which,

FIG. 1 is a perspective view of a control valve, of the three-way valvetype, according to one embodiment of the invention;

FIG. 2 is a view in section of the control valve for FIG. 1, the planeof section passing through the axis of rotation of the adjusting member;

FIG. 3 is a corresponding view in section of the adjusting member and ofthe sealing ring with which it is fitted;

FIG. 4 is a schematic view in section of the control valve of FIGS. 1and 2, the plane of section being perpendicular to the axis of rotationof the adjusting member;

FIG. 5 is a perspective view of the sealing ring;

FIG. 6 is a view in cross section of the sealing ring of FIG. 5;

FIG. 7 is a detail on a larger scale of FIG. 6;

FIG. 8 depicts the developed surface of the sealing ring, without theblind holes;

FIG. 9 is a view similar to FIG. 8 with the blind holes; and

FIG. 10 depicts a motor vehicle combustion engine cooling circuitequipped with a control valve according to the invention.

FIGS. 1 and 2 show a control valve 10 which comprises a cylindrical body12 bounded by an end wall 14 and a cylindrical side wall 16 of axis XX.A fluid inlet duct 18 opens axially into the end wall 14. Three fluidoutlet ducts 20, 22 and 24 open into the cylindrical side wall 16. Inthe example, the outlet ducts 20, 22 and 24 open radially into the wall16. The ducts 20 and 24 are diametrically opposed, while the duct 22makes an angle of 90° to the common axis of the ducts 20 and 24.Furthermore, the ducts 20, 22 and 24 have successively decreasingdiameters.

Housed inside the valve body 12 is an adjusting member 26, also known asa rotary member, produced in the form of a generally cylindrical elementextended by a rod 28 directed along the axis XX. This rod 28 passesthrough a central opening exhibited by a cover 30 of circular shape.This cover is screwed onto a flange 32 of the valve body by means offour fixing screws 34, with the interposition of a seal (not depicted).The adjusting member 26 is driven in rotation about the axis XX bymotorizing means 36 depicted schematically in FIG. 1. These may, forexample, be a motor of the stepping type able to bring the adjustingmember 26 into a multitude of different positions, either in successiveincrements or continuously.

The adjusting member 26 comprises a truncated end 38 consisting, in theexample, of a planar face 40 forming an angle close to 45° with the axisof rotation XX. Thus, the adjusting member 26 allows the fluid outlets20, 22 and 24 to be controlled with a law defined according to itsangular position in the valve body.

According to the invention, the adjusting member 26 is surrounded, overpart of its periphery, by a sealing ring 42 in the form of an openannulus, which rotates as one with the adjusting member and is able tocome into sealing contact with the internal face of the side wall 16.This sealing ring, the shape of which is better apparent in FIGS. 5 to7, is arranged with a small clearance j (FIG. 3) around the adjustingmember. This allows the fluid entering the valve body via the inlet duct18 to exert pressure directed radially outward and acting against theinterior of the sealing ring 42 so as to press it firmly radiallyagainst the side wall 16 with a view to ensuring sealing. This pressureis shown by the radial arrows P in FIG. 4. This FIG. 4 constitutes aschematic drawing and, in particular, the adjusting member 26 isdepicted schematically, the clearance there is to the sealing ringhaving been deliberately very much exaggerated.

As can be seen more particularly in FIGS. 5 and 6, the sealing ring 42,in the form of an open annulus, has a generally cylindrical surfacewhich hugs the truncated shape of the envelope of the adjusting member26. The ring 42 is bounded at its top by an edge 44 in the shape of anarc of a circle, at its bottom by an edge 46 also in the shape of an arcof a circle, by two edges 48 and 50 generally parallel to the axis andby inclined edges 52 and 54. A cutout 56 formed from the edge 44 is alsoprovided. On its interior face, the ring 42 comprises ribs 58, parallelto the axis, each intended to collaborate with a groove 60, alsoparallel to the axis, formed at the periphery of the adjusting member(FIG. 6). This allows the sealing ring to rotate as one with theadjusting member and allows the fluid to enter the intermediary spacebetween the adjusting member and the sealing ring.

The sealing ring is made of a material with a low coefficient offriction, for example polytetrafluoroethylene (PTFE), or alternatively apolyamide, etc. In order to further reduce the friction between thesealing ring and the internal face of the side wall 16, this sealingring comprises a smooth exterior surface into which a multitude ofuniformly distributed blind holes 62 open. These blind holes are betterapparent in FIGS. 5 to 7. As can be seen in the figures, each of theblind holes, that is to say holes which are not through-holes, has acircular contour. In the example, each of the blind holes has the fromof a cap of a sphere (see FIG. 7).

In the exemplary embodiment depicted, the rib 58, that can also be seenin the detail of FIG. 7, is bounded by two radial walls 64 which make anangle A between them, here 30°. The radial walls 64 meet an interiorface 66 of the sealing ring, opposite an exterior face 68 in which theblind holes 62 are formed (FIGS. 6 and 7).

Here, the blind holes each have a diameter (D) suitably chosen accordingto the axial spacing and the radial spacing between the blind holes.

FIG. 8 depicts the smooth surface area SL of the sealing ring, withoutthe blind holes 62.

FIG. 9 depicts the same surface area with the blind holes 62. The totalsurface area of the blind holes is here denoted ST.

A ratio R between the surface area of the blind holes and the smoothsurface area SL may be defined; here R=ST/SL, and this can be used tocharacterize the percentage of the smooth surface area occupied by theblind holes in question. In general, it is advantageous for this ratio Rto be between 25% and 40%, preferably close to 33%.

In one exemplary embodiment, the smooth surface area SL is 4473 m². Theblind holes 62 each have a diameter of 3 mm and are separated from oneanother by an axial spacing of 4 mm and a radial spacing of 4.45 mm. Asa result, the surface area ST here is 1428 m², which gives a ratio Rmore or less equal to ⅓ or 33%.

As a result, under these conditions, the frictional torque between thesealing ring and the valve body is reduced by approximately ⅓ bycomparison with the frictional torque that would result from a sealingring that had a smooth surface.

Under these conditions it is possible, all other things being equal, touse lower powered motorizing means 36, and to do so without compromisingthe sealing characteristics.

The valve of the invention finds a particular application in the fieldof motor vehicles. FIG. 10 shows a circuit 70 for cooling the combustionengine 72 of a motor vehicle. The circuit 70 has, passing through it, acooling fluid, usually water with an antifreeze added, which circulatesunder the action of a pump 74. The fluid, heated up by the engine,leaves the engine via an outlet 76 which is connected to the inlet duct18 of a control valve 10 of the type described hereinabove. This valvecomprises three outlet ducts 20, 22 and 24 which are connected to threebranches of the circuit.

This circuit comprises a first branch 78 which contains a coolingradiator 80 and an expansion tank 82, a second branch 84 which bypassesthe cooling radiator 80 and the expansion tank 82, and a third branch 86which contains a heater matrix 88 used to heat the cabin of the vehicle.

The duct 20 is connected to the branch 78 (radiator), the duct 22 isconnected to the branch 86 (heater matrix) and the duct 24 to the branch84 (bypass). The valve thus allows the flow rates of fluid in the threeaforementioned branches of the circuit to be controlled independently soas to optimize the temperature of the combustion engine and the heatingof the cabin.

Of course, the invention is not restricted to the embodiment asdescribed hereinabove and applies to other variants. Thus, the shape ofrevolution defined by the valve body is not necessarily cylindrical andcould, for example, be conical or frustoconical. The number and mutualarrangement of the outlet ducts can also be varied in numerous waysaccording to the applications considered.

In general, the valve of the invention finds a particular application inthe motor industry.

1. A control valve for a fluid circulation circuit, comprising a body(12) which is equipped with a fluid inlet (18) and with at least twofluid outlets (20, 22, 24) and which delimits a housing of revolutionfor an adjusting element (26) able to rotate about an axis of rotation(XX) and to adopt various angular positions to control the distributionof fluid through the outlets, the body (12) comprising an end wall (14)into which the fluid inlet opens and a side wall (16) into which thefluid outlets open, characterized in that the adjusting member (26) issurrounded by a sealing ring (42) in the form of an open annulus, whichrotates as one with the adjusting member (26) and is arranged with asmall clearance (j) around the adjusting member, this allowing thesealing ring to be pressed firmly internally against the side wall (16)with a view to ensuring sealing under the action of the pressure (P) ofthe fluid.
 2. The control valve as claimed in claim 1, characterized inthat the sealing ring (42) is made of a material with a low coefficientof friction.
 3. The control valve as claimed in claim 2, characterizedin that the material with a low coefficient of friction is chosen frompolyamides and polytetrafluoroethylene.
 4. The control valve as claimedin one of claims 1 to 3, characterized in that the sealing ring (42)comprises a smooth exterior surface into which a multitude of uniformlyspaced blind holes (62) open, this making it possible to reduce the areaof contact between the sealing ring (42) and the side wall (16).
 5. Thecontrol valve as claimed in claim 4, characterized in that the ratio (R)between the surface area (ST) of the blind holes (62) and the smoothsurface area (SL) of the sealing ring (42) is between 25% and 40%,preferably close to 33%.
 6. The control valve as claimed in one ofclaims 4 and 5, characterized in that the blind holes (62) have acircular contour.
 7. The control valve as claimed in claim 6,characterized in that the blind holes (62) have the form of caps of asphere.
 8. The control valve as claimed in one of claims 1 to 7,characterized in that the adjusting member (26) and the sealing ring(42) have reliefs (58, 60) of mating shapes to allow them to be made torotate as one.
 9. The control valve as claimed in one of claims 1 to 8,characterized in that the side wall (16) of the valve body delimits acylindrical housing and in that the sealing ring (42) has a cylindricalexterior surface.
 10. The control valve as claimed in one of claims 1 to8, characterized in that the fluid inlet (18) opens axially into the endwall (14), and in that the fluid outlets (20, 22, 24) open radially intothe side wall (16) of the valve body.
 11. A fluid circulation circuit,characterized in that it comprises a control valve as claimed in one ofclaims 1 to 10, the fluid inlet (18) of which is connected to a fluidsource (76) and the fluid outlets (20, 22, 24) of which are connectedrespectively to branches (78, 86, 84) of the circuit.
 12. The fluidcirculation circuit as claimed in claim 11, characterized in that it isproduced in the form of a cooling circuit (70) for the combustion engine(72) of a motor vehicle, through which a cooling fluid passes under theaction of a circulation pump (74), and in that the control valve (10) isa three-way valve, the fluid inlet (18) of which is connected to anintake (76) for cooling fluid arriving from the engine (72) and thethree fluid outlets (20, 22, 24) of which are connected respectively toa first branch (78) of the circuit which contains a cooling radiator(80), to a second branch (84) of the circuit which bypasses the coolingradiator (80), and to a third branch (86) of the circuit which containsa heater matrix (88) for heating the cabin.